If I remember correctly, there may have been an issue with writing to the DFS when this code was written. During the suspend or migrate of a non-persistent VM, the writing of the state needed to be very fast in order to take a snapshot of the state, and continuously sync the new changes until the current state was in sync with what was copied to disk. In our case, the DFS was not a high performance filer but just a machine with jbod attached disks. I think Mike would be able to give more details about this one.
RIchard On Fri, Mar 23, 2012 at 2:23 PM, Michael Stroucken <[email protected]> wrote: > I'm looking at improving the speed with which VMs can be suspended or > migrated, and I'd like to make a change to streamline things. > > Currently, when a machine suspends, it writes its state to the local file > system. Once the dump is complete, the state file is copied into the DFS. On > resuming though, the state file is fed directly to qemu from the DFS. > > I'd like to eliminate the copy and store the state file directly into DFS. > In my case, the DFS is a mount on a filer, provided courtesy of Netapp. > Writing directly to the Netapp cuts out a potential failure location plus it > provides higher performance versus the local drive. > > I think it is a win, but I wanted to make sure that the suspend > functionality wasn't intentionally organized this way. > > Thanks, > Michael. -- Richard Gass
